Assessing smoke toxicity of burning combustibles by four expressions for fractional effective dose

Toxicity of smoke generated in a fire is difficult to measure accurately. That is because gas sensors for measuring rapidly varying concentrations of toxic gases are not yet developed. Simple expressions are searched for quick measurement in assessing smoke toxicity practically. Four equations on calculating fractional effective dose (FED) related to toxic effluents were reported in the literature, each based on different assumptions. FED value was proposed to be calculated based on peak carbon monoxide concentration and peak carbon dioxide concentration, and transient carbon monoxide, carbon dioxide, and oxygen concentrations. The four values were compared in this article using literature data on toxic gases from different materials measured by (i) cone calorimeter; (ii) full-scale burning tests; and (iii) tunnel full-scale tests. Measured carbon monoxide, carbon dioxide, and oxygen concentrations by standard equipment of oxygen consumption calorimeters were used to calculate the four FED values. It is found that the values of FED based on peak carbon monoxide and carbon dioxide concentrations (denoted as FED₂) are similar to the average values of FED calculated from the updated equation in the literature using the oxygen consumption calorimeters. Putting the values of FED₂ in fire safety design guides is then recommended.     

New approaches to determine the interface height of fire smoke based on a three-layer zone model and its verification in large confined space

Large confined space has high incidence of fires, which seriously threatens the safety of people working there. Understanding the distribution of smoke in such large space is critical to fire development prediction and smoke control. Three improved methods for the stratification interface prediction of fire smoke are developed, including of improved intra-variance, integral ratio and N-percentage methods. In these methods, the interface height is determined by the vertical temperature distribution based on a three-layer smoke zone model, which is an improvement of a two-layer zone model. Thereafter, the three improved methods are applied to several typical fire cases simulated CFD to predict the smoke interface, and their applicability and reliability are verified by comparison of the smoke stratification results with the filed simulation results. Results show that the three improved methods can effectively determine the location of the three-layer zone model's interface, and they have the ability to predict smoke interface for fires with different fire source types and ventilation conditions.     

Color design of cigarette packaging for reducing smoking rate in youth

Since smokers are becoming younger and younger, it is necessary to curb the tobacco epidemic at a younger age to prevent the devastating damage caused by tobacco products to future generations. This study focuses on the color schemes of cigarette packaging. It aims to find out color schemes of teenage consumers' disgust and apply them to cigarette packaging, which ultimately reduces the desire of purchasing and the smoking rate of young people. First, there were two ways to acquire color schemes. One was to extract the color schemes that can make teenagers disgust and keep them away from cigarette by association of psychological adjectives. The other way was to match achromatic colors with the chromatic colors that teenagers dislike in the questionnaire of 126 colors. Finally, eye movement experiment was used to verify the acquired color schemes meet the expected objectives of this study. A new idea to reduce the smoking rate of teenagers was proposed, and a method for the color design of cigarette packaging was provided.     

Mechanism of smoke suppression by melamine in rigid polyurethane foam

The smoke suppression of rigid polyurethane foam (RPUF) modified by melamine was investigated based on three sections: the condensed phase, the carbon layer, and the gas phase. In the condensed phase, the results of thermogravimetry, X‐ray photoelectron spectroscopy (XPS) N1S spectrum, and Fourier transform infrared spectroscopy indicated that melamine could suppress the degradation of RPUF by reacting with the aromatic hydrocarbons. It also reduced the smoke generation because the volatilizable aromatic hydrocarbons were the principal smoke precursors in a fire. In the carbon layer, the decrease from 38.50% to 24.76% of the inner layer oxygen content identified by XPS full‐spectrum and C1S spectrum indicated that melamine could prevent oxygen from transferring into the inner foam by the formation of an enhanced surface carbon layer, and the enhanced carbon layer could also block the release of smoke precursors. In the gas phase, the content of total aromatic hydrocarbons declined to 59.12% according to pyrolysis gaseous chromatography mass spectroscopy and indicated that melamine could reduce the smoke precursors. The results of smoke density chamber and cone calorimeter tests revealed that the addition of the melamine could decrease the smoke density of burning RPUF. Copyright © 2014 John Wiley & Sons, Ltd.     

某型柴油机排烟温度异常故障排查与分析

针对某油船主推进柴油机排烟温度异常升高的故障,从引起柴油机排烟温度异常升高的可能因素着手进行排查.结果表明:排烟波纹管内衬套开裂脱落,堵塞排烟管是导致排烟温度异常升高的直接原因.指出:案例中的这个因素虽比较少见,但还是有迹可循;可为船舶柴油机的使用管理与维修实践提供一定借鉴.     

Measurement of chemical emission rates from cigarette butts into air

This study examined airborne emissions from cigarette butts for styrene, 2-methyl-2-cyclopenten-1-one, naphthalene, triacetin, and nicotine. Ten experiments were conducted by placing butts in a stainless steel chamber and measuring the chemical concentrations in chamber air. Emission rates were determined from the concentrations. Triacetin and nicotine concentrations were roughly 50% of initial concentrations after 100 hours, while concentrations of other chemicals decayed to less than 10% of initial concentrations within 24 hours. Initial emission rates per cigarette butt ranged from 200 to 3500 ng h⁻¹. Triacetin and nicotine emission rates at 25°C were 1.6 to 2.2 times higher than the rates at 20°C, while the emission rates of other chemicals at 25°C were 1.1 to 1.3 times higher than the rates at 20°C only during the first sampling period. The chemical concentrations and emission rates at 30°C were comparable or lower than the values at 25°C, possibly due to different batches of cigarettes used. The 24-hours emitted mass of nicotine from a cigarette butt at 25°C could be up to 14% of the literature reported nicotine masses emitted from a burning cigarette.     

火源横向位置对隧道烟气分布的影响

依托工程实际,采用数值模拟方法研究隧道火源位于不同车道时,隧道临界风速、温度、烟雾分布扩散规律。结果表明:纵向通风速度不大于临界通风速度时,火源下游段隧道棚顶温度呈e函数下降,当通风速度大于临界通风速度时,该规律不再适用。火源位于侧壁面时,由于隧道侧壁面的限制作用,其近火源区烟气运移呈“之”字形向隧道出口处蔓延,隧道棚顶不同纵向温度线呈滚动式交替变化。     

新中国早期产品品牌命名和设计范式探究——以烟标为例

新中国早期产品品牌的命名和设计,在政治内容、审美趣味与商业企图之间获得了平衡。构建了易于被大众接受,群众喜闻乐见,紧随时代潮流的命名和设计范式。其中,以烟标最为典型,散发出鲜明的视觉特色和独有魅力,给人们留下诸多的回忆。为新中国立国建国、经济建设、航天国防、友好和平和文化生活等方面信息的传播和价值观的塑造,作出了不可忽视的贡献,也为现代产品品牌的命名和设计提供了早期的范式参考。     

Experimental study of the combustion characteristics of methanol‐gasoline blends pool fires in a full‐scale tunnel

The combustion characteristics of methanol‐gasoline blends pool fires were studied in a series of full‐scale tunnel experiments conducted with different methanol and gasoline blends. The parameters were measured including the mass loss rate, the pool surface temperature, the fire plume centerline temperature, the ceiling temperature, the smoke layer temperature profile, the flame height, and the smoke layer interface height. The gasoline components were analyzed by GC‐MS. The effects of azeotropism on the combustion characteristics of the different blends were discussed. On the basis of the results of the fire plume centerline temperature, the ceiling temperature, and the flame height, it shows that the tunnel fire regime gradually switches from fuel controlled to ventilation controlled with increasing gasoline fractions in the blends. The fire plume can be divided into 3 regions by the fire plume centerline temperature for the different blends. The N‐percentage rule to determine the smoke layer interface height is found to be applicable for tunnel fires with different blends for N = 26.